First additions

Hi Michael,

I added the record and two examples.  I documented one of the examples. The other example refers to the documentation of the first example.
The pump now by default uses the record 'PumpData' to get its parameters instead of using regular default values. This however seems to cause problems because these defaults cannot be overridden anymore. For example:
```
Check of Buildings.Fluid.Movers.Examples.FlowMachine_Nrpm:

Record has a value, and attempt to modify specific elements.
The element modification of e.g. V_flow will be ignored.
Modelica Text: near line 7
Attempted overriding found at:
Modelica Text: line 7
```
I do not know a solution for this.

I'll add more examples based on any feedback.

Also, I suppose an example similar to issue #202 (https://github.com/lbl-srg/modelica-buildings/pull/202) is in order?

Thanks!

Filip